Decibels (Math Chat) - Frank Morgan, MAA Online
Challenge: The Christian Science Monitor of July 8, 1999, reports that "according to the NRDC, the amount of ambient noise in the ocean may have increased by 10 decibels - in other words, 10-fold - between 1950 and 1975." Is this correct?
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Deep in the Jungles - Ivars Peterson (MathTrek)
Humans are predisposed to seeing order and meaning in a world that too often presents random choices and chaotic evidence. Random events sometimes get linked into a meaningful, though ultimately bogus, scenario... At the same time, the mathematics of
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Defending the Roman Empire - Ivars Peterson (MathTrek)
Questions of military strategy can be handled mathematically. Charles S. ReVelle of Johns Hopkins University in Baltimore and Kenneth E. Rosing, recently retired from Erasmus University Rotterdam, describe their approach in the August-September American
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The Definitive Four Fours Answer Key - David A. Wheeler
From 0 up to 40,000, whole number mathematical expressions that use only common mathematical symbols and exactly four 4s. Wheeler offers his solutions in three different formats: an abbreviated list of answers; a text file of results, mathematical expressions,
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Dennis Stanton
Dennis Stanton is a professor at the University of Minnesota studying combinatorics and hypergeometric functions. Many of his papers are available online in PostScript and PDF formats. There are also exams and solutions from previous classes, and a complete
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Developing Algebraic Thinking - Suzanne Alejandre
Teacher lesson plan and student kinesthetic activities on the Traffic Jam activity and applet, as originally published in the inaugural (Fall, 2002) issue of ON-Math, an electronic journal of the National Council of Teachers of Mathematics (NCTM).
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Different Ways to Represent Numbers - Chad Lake
Online paper that discusses and illustrates counting in bases other than 10; converting to decimal; the Snake Algorithm (the algorithm, summary of binary-to-decimal Snake Algorithm, decimal-to-binary Snake, extending the Snake to other bases, and summary
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Disorder in the Deck - Ivars Peterson (MathTrek)
About 30 years ago, tournament bridge players started using computer-shuffled rather than hand-shuffled decks. Almost immediately, there was an outcry protesting the apparently wild fluctuations in the distribution of cards of different suits in computer-dealt
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Dividing The Plane - Jim Loy
A line divides the plane into two pieces (regions). Draw another line. The plane is now divided into three or four regions. It is three regions if the lines are parallel, four if they intersect. A third line divides the plane into seven regions. Find
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Division by Three [PDF] - John Conway, Peter Doyle
A formal proof that it is possible to divide by three. This assertion is easy to prove using the axiom of choice, but becomes a much more difficult problem if the axiom of choice is not allowed (as is the case here). From this proof, and the much simpler
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D. J. Bernstein
Courses, research articles (in dvi format), and a list of available software, listed by a professor of mathematics and computer science at the University of Illinois. Pages are also listed by topic. Also at ftp://koobera.math.uic.edu/www/djb.html.
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DNA Adds Up - Ivars Peterson (MathLand)
Calculating that 0 + 0 = 0, 1 + 0 = 1, and 0 + 1 = 1 is normally no big deal. When the calculations are done in the lab using DNA molecules, however, these elementary manipulations look considerably more interesting. In the July 12 [1996] Science, a team
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Dominique Foata
Dominique Foata is a mathematician specializing in combinatorics. Abstracts of his papers are available online, and they may be downloaded in .dvi, PostScript, or TeX formats. The site also contains a summary and errata for the textbook Calcul des Probabilités,
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